Calcium responses of chicken trigeminal ganglion neurons to methyl anthranilate and capsaicin

Using digital fluorescence imaging, we determined the effects of methyl anthranilate (MA), an avian irritant, and capsaicin (CAP), a mammalian irritant, on intracellular calcium ([Ca2+]i) in chicken trigeminal neurons. Concentration–response functions indicated that the threshold for inducing increases in [Ca2+]i was higher for CAP (30·mmol·l–1) than for MA (10·mmol·l–1). The maximum magnitudes of [Ca2+]i in response to MA and CAP were compared after normalization to 40·mmol·l–1 KCl. At equal concentrations (300·mmol·l–1), trigeminal neurons responded with a greater change in [Ca2+]i to MA (78% of KCl) than to CAP (43% of KCl). Furthermore, at 300·mmol·l–1, 48% of neurons responded to MA whereas only 16% responded to CAP. The increases in [Ca2+]i induced by both MA and CAP were dependent upon extracellular calcium. While the calcium responses to MA were also dependent on extracellular sodium, responses to CAP were not. There were separate but overlapping populations of neurons sensitive to MA and CAP. Taken together, the higher threshold concentration of CAP, the higher response magnitude to MA than CAP and the greater number of neurons sensitive to MA than CAP provide a rationale for the observed behavioral differences of birds to these two compounds. Finally, the findings that the calcium responses to MA and CAP have different ion dependencies and that there are separate populations sensitive to these compounds suggest different transduction mechanisms mediating chicken trigeminal responses to MA and CAP

Piet Mondrian's trees and the evolution in understanding multiple sclerosis, Charcot Prize Lecture 2011

Item does not contain fulltextFour questions were posed about multiple sclerosis (MS) at the 2011 Charcot Lecture, Oct. 22, 2011. 1. The Male/Female Disparity: Why are women developing MS so much more frequently than men? 2. Neuronal and Glial Protection: Are there guardian molecules that protect the nervous system in MS? 3. Predictive Medicine: With all the approved drugs, how can we rationally decide which one to use? 4. The Precise Scalpel vs. the Big Hammer for Therapy: Is antigen-specific therapy for demyelinating disease possible? To emphasize how our views on the pathogenesis and treatment of MS are evolving, and given the location of the talk in Amsterdam, Piet Mondrian's progressive interpretations of trees serve as a heuristic